hey, umm. don't put any in the middle, get some stuff called Liquid Nail or stuff like that, comes in a tube. put that down in the middle, put screws at the ends and put a in to middle of the two screws on the edges, and keep putting more in the middle until they're all evenly spaced. so, on the edges evenly spaced, and liquid nails in the middle.

i've done the counter sinking liek that and i've caught that counter sink area with my edges every time. and if you use liquid nails you cover a more througho area instead of only where the screws are to hold it down.